Percussive tool



July 31, 1928. 1,679,130

- H. H. MERCER PERCUS S IVE TOOL Filed. June 15; 1921 2 Shun-sheet 2 J v. 0-2 a0 Patented July 31, 1928.

UNITED STATES 1,679,130 PATENT orrics.

HENRY n. MERCER. or crassivio'nr, new narlrrsiiinn, ASSIGNOR 'ro SULLIVAN M'A- cnrnnn-Y COMPANY, A CORPORATION OF MASSACHUSETTS.

PERCUSSIVE TOOL.

Application filed June 13,

This invention relates to tools or machines which are operated by percussive action and especially, although not exclusively, to, fluid pressure operated rock channeling machines.

In the operation of such machines, it frequently happens that, when the tool or bit is not properly in engageiinent with the work, as where the machine has been lifted from the work without stopping the same, or where a fissure, body of comparatively soft material, or other relatively non-resistant spot or region is unexpectedly encountered, the percussive action of the machine, not being imparted to and taken up by the work in the intended manner, reacts upon or is delivered to the machine itself with consequent damage to the latter. Thus, for example, in the case of a steam channeling machine employing a cylinder and a piston therein for reciprocating the toolcarrying cross head, it is customary to drive the piston downwardly with considerable force until its motion is arrested by the impact of the tools against the rock, and should said tools fail to strike the rock, or should said rock be of such a soft character as not to ar 'estthe tools, before'thc piston reaches the lower end of the cylinder, the latter is repeatedly struck or hammered by said piston and has, in many instances, beenseriously damaged iii-this manner. I

The present invention has for its object to provide means, applicable to channeling and other percussive machines, whereby, in. the event of failure of the 'tool or tools to be arrested by the work before the actuating means therefor reaches the limit of its movement, the impact of said actuating means thereafter will be automatically cushioned in order to prevent inpiry thereto.

The foregoing and other objects of inven-' tion, together with means whereby the same may be carried into effect, will best be under? stood from the following description of one form or embodiment thereof illustrated in the accompanying drawings,in which 1 Fig. 1 is a side elevation of a channeling .machine having the invention applied thereto. i a

Fig. 2 is an enlarged side elevation of the operating and controlling devices for the cushioning means, showing the same in normal or inoperative position;

Fig. 3 is a similar view showing the parts in the operative or cushioning position.

1921. Serial No. 477,040.

Fig. 4 is an enlarged sideelevation, partly tributing valve.

Fig. 5 is a horizontal section on the line 5-5 of Figs. 2 and 4.

Fig. 6 is an enlarged vertical section taken substantially on the line 66 of Fig. 3.

I Fig. 7 is detail View of thespring for operating the cushioning valve.

, The invention is herein shown as applied to a channeling machine of well known construction comprising a wheeled truck (Fig. 1) having a trunnion bar l 6 on which is adjusta-biy mounted'a standard 17 carrying a head 18 vertically movableon said standard by means of a feed screw 19. The 1 head 18 carries a cylinder 20 containing a piston 21 (Fig. 4) having a piston rod 22 for reciprocating a cross head 23 carrying the usual gang of channeling tools 24.

The parts thus farreferred to may be of any usual or suitable construction and, being well known in the art, will not be described in detail herein.

The cylinder 20 is provided with upper and lower, inlet-lmssa'ges 25 and 26 (Fig. 4)

. and with upper and lower exhaust passages 27 and 28 controlled by a-distributing valve 29 in the valve casing 30, said distributing valve being inturn controlled by a pilot valve 31 also located in tliecasing and havinga stem 32 (Figs. 1 and 2) connected by link 33 with a. lever 34 pivoted on a stud 35projectin-g from the head 18. The lever 34 is connected by a link '36 with the cross head 23, whereby the pilot valve 31' is operated and the distributing valve 29 shifted in order to reverse the movement of the piston 21. I The valve mechanism above described is illustrative of suitable fluid pressure disiributin'g means for causing reciprocation of the piston 21 and tool carrying cross head 23-wh'ich means may, however, be of any suitable constructi on and arrangement usual in the art.

In accordance with the usual custom, the inlet passage 25 communicates with the extreme upper endof the cylinder 20 while the-lower inlet passage 26 cominunicates with said cylinder at aslrortdistance above-the bottom thereof, the upper and lower exhaust passages 27 and 28 being located, respectively, below and above said inlet passages 25 and 26. During the normal operation of the mechanism, steam flows past the distribution valve 29 to the inlet passage 25 to the upper end of the cylinder 20, the fluid acting on the upper surface of the piston 21 forcing the latter downwardly, it being understood that the lower end of the cylinder is opened to exhaust through the exhaust passage 28under the control of the distribution valve 29. As the piston 21 moves downwardly the lever 34 of the valve gear mechanism actuates the pilot valve 31, consequently effecting the shifting of the distribution valve 29 to out off the supply of steam flowing through inlet passage 25 and to close exhaust passage 28, the inlet passage 26' and the exhaust passage 27 then being opened. The piston 21 continues its downward travel by momentum and steam expansion until it reaches a position adjacent the lower cylinder head. The rebound of the tools from against the work and the compression built up in the front end of the cylinder effect movement of the piston 21 rearwardly until the inlet passage 26 is uncovered by the piston head. Live steam then flows through the inlet passage 26 and acts on the lower surface of the piston, forcing the latter upwardly, the upper end of thec'ylinder being opened to exhaust through passage 27 at that time. As the piston moves upwards the inlet valve is shifted, reversing the position of the distribution valve. In the normal operation of the machine, the distributing valve 29 is usually shifted to cut off the steam from the upper end of the cylinder when the piston, on its downstroke, reaches approximately the position shown in full lines in Fig. 4, said piston, however, continuing to travel, by momentum, until itreaches approximately a position, shown in dotted lines in said figure, just above the lower cylinder head, in order to cause the tools 24 to strike a resilient blow. The amount of cushioning steam which creates this so called resilient blow is merely for the purpose of obtainingquick return of the piston. In the event of the failure of the tool 24 to properly strike the rock, the downward impulse of the piston 21 sometimes carries it below the intended downward limit of its movement and by reason of the fact that the amount of the steam which is in the lower end of the cylinder during normal operation of the device is not of sufficient volume to provide suilicient cushioning during an abnormal stroke of the mechanism, the piston would without my improved means cause repeated blows of suflici-ent violence to be created within the cylinder head thus seriously to injure the machine. In order to prevent such an occurrence, and in accordance with the present invention, the following mechanism is provided.

Located in the lower exhaust passage 28 is a rotary throttle valve 37 (Figs. 4, 5, and

6) having a stem 38 rotatably mounted in a bushing 39 in threaded engagement with the wall of the valve casing 30, said bushing forming a fluid tight joint with a shoulder 40 on the end of the valve 37, which shoullever 44 secured to the end of the stem 38 by a nut 45. The bushing 39 is formed with the exterior shoulder 46 which engages and secures to the valve casing 30 one end of a bracket or support 47, the opposite end of which is secured to said valve casing by bolts 48 (see also Figs. 2 and 3). Rotatably mounted on the outer end of the bushing 39 is a hub 49 having a segmental flange 50 the end of which forms a shoulder 51 which is slightly offset into a position to engage the operating lever 44. The flange 50 is pro vided with a resetting finger-piece 52 and with a locking shoulder 53 which is normally engaged. by a detent 54 on the upper end of a latch rod 55 guided for longitudinal move ment in a sleeve portion 56 of the bracket 47. The latch rod 55 is normally pressed upwardly by a spring 57 to force thedetent 54 into engagement with the locking shoulder 53, thereby holding the hub 49 in the position shown in Fig. 2 against the tension of a spring 58 (Figs. 5, 6, and 7) connected at one end 58 (Figs. 2, 3, and 7) to a flange 59 on the bracket 47 and at its opposite end 58 to the hub 49, said spring tending to turn said hub from the position shown in Fig. 2 into that shown in Fig. 3. The latch rod 55 is connected at its lower end to an arm or lever (51 pivoted on the stud 35 con stituting the fulcrum of the lever 34, said arm 61 carrying at its outer end an adjustlit] able abutment screw 62 adapted to be engaged by said lever 34.

In the normal operation of the machine, the hub 49 is restrained by the detent 54, and the operating lever 44 occupies the. position shown in F igs.'1 and 2, in which position the valve 37 is in a position to tully open the exhaust passage 28, as shown in Fig. 4. Should the cross head 23 and piston 21, due to failure of the tools 24 to engage the work, descend below a predetermined position, which position may be determined by adjustment of the screw 62, the lever 34 will engage said screw and rock the arm 61, thereby depressing the latch rod 55 and moving the detent 54- out of engagemei'it with the Fig. 3 causes the valve 37 to be turned to close the exhaust passage 28,-a s shown in dotted lines in Fig. 4, thereby trapping steam in the lower end of the cylinder 20, "forming a fluid cushion which checks the downward movement of the piston 21011 its nextand Succeeding strokes, and preventing further hammering oi the lower cylinder head.

The parts may be reset by turning the hub 49 by means of the finger-piece 52 until the shoulder 53 is re-engaged by the detent 54, after which the lever-44 may be operated by hand to open the valve 37. In order to tacilitate the latter operation, said lever 44 may be connected at its outer end with a manually operated rod 64 extending to the opposite sides of the head 18 and provided with suitable handles 65, said rod being also operable to close the valve 37 manually, should occasion arise to do so. In the latter connection, it will be noted that a lost motion connection is provided between the hub 49 and lever 44, whereby, when the hub 49 is held in normal position by the detent 54,

the lever 44, and consequently the valve 3?,

is nevertheless tree to be moved by hand from the position shown in Fig. 2 into that. shown in Fig. 3 to close the valve 87. It will also be noted that the operation oi the hub 49, under the influence of the spring 58, is such as to cause the shoulder 51 to strike the lever 44 a sharp blow, thereby quickly moving the same from the position shown in Fig. 2 into thatshown in Fig. and producing a nearly instantaneous closing of the valve 37.

From the foregoing it will be seen that means have been provided for eiiectually checking and cushioning the operation of a percussive tool should the tool fail to en counter the normal resistance of the work, thereby preventing damage to the mech anism caused by the impact or hammering of the mechanism upon itself instead of upon the work, said means being of extremely quick action and being capable of adjust ment in order to meet varying conditions.

\Vhile I have in this specification shown and described in detail one embodiment 7 controlled by an element of said distribution means for automatically cheekingan abnormal movement of said piston when a decreasing resistance is encountered by said tool, said element of said distribution means being adapted to eitec't a striking action, said automatic checking means including an element automatically released by said strik ing element upon abnormal movement of said piston.

' 2. The combination with a percussive mechaniam including relatively reciprocable cylinder and piston elements, a tool actuated thereby, and fluid distribution means therefor having inlet and exhaust passages, and a distributing valve for controlling said passages, of means including a throttle valve in one of said exhaust passages and an operating member for said controlling valve controlled by an element of said distribution means for automatically cushioning said piston upon abnormal movement thereof when a decreasing resistance is encountered by a striking element associated with said operating member adapted to have a striking action upon the same, and means operated by said tool for releasing said striking element. The combination with a percussive mechani'sn'i including relatively reciprocable cylinder and piston elements, a tool actuated thereby, and fluid distribution means therefor includin fluid distributin aassa 'es forv b t) b automatically checking the movement thereof when said tool encounters a decreasing resistance, said automatic means including means for controlling fluid flow in one of said fluid distributing passages.

4. The combination with a percussive mechanism including relatively reciprocable cylinder and piston elements, a tool actuated thereby, andfluid distribution means therefor including fluid distributing passages, of means controll-edby an abnormal stroke of one of said elements for automatically cushioning the percussive thereof when said tool encounters a decreasing resistance,said automatic means including a valve for controlling fluid flow in one of said fluid distributingpassages.

5. The combination with a percussive mechanism including relatively reciprocable cylinder and piston elements, a tool actu ated thereby, and fluid distribution means thereforincluding a fluid distributing pas sage, of means-controlled by an abnormal stroke of said piston for automatically checking the movement thereof when said action lot) tool encounters a decreasing resistance, said I automatic. means including a throttle valve for controlling fluid flow through said fluid distributing passage.

6. The combination with a percussive mechanism including relatively reciprocable cylinder and piston elements,a toolactuated including a throttle valve for controlling fluid flow through said exhaust passage.

7. The combination with a percussive mechanism including relatively reciprocable cylinder and piston elements, a tool actuated thereby, and fluid distribution means therefor, of means controlled by an abnormal stroke of one of said elements for automatically checking the movement thereof when said tool encounters a decreasing resistance, said automatic means including means for interrupting normal fluid flow relative to said cylinder.

8. The combination with a percussive mechanism including relatively reciprocable cylinder and piston elements, a tool actuated thereby, and fluid distribution means therefor including inlet and exhaust passages, of means controlled by an abnormal stroke of one of said elements for checking the movement thereof when a decreasing resistance is encountered by said tool, said automatic means including means for cutting off the flow of exhaust fluid from the forward end of said cylinder through one of said exhaust passages.

9. The combination with a percussive mechanism including relatively reciprocable cylinderand piston elements, a tool actuated thereby, and fluid distribution means therefor including inlet and exhaust passages, of means including a throttle valve in one of said exhaust passages, and means automatically controlled by an abnormal stroke of said piston for operating said throttle valve, and means for resetting said automatic means independently of said throttle valve.

10. The combination with a percussive mechanism including relatively reciprocable cylinder and piston elements, a tool actuated thereby, and fluid distribution means therefor including inlet and exhaust passages, of means including a rotary valve for controlling one of said exhaust passages, means for operating said valve, and means controlled by an abnormal stroke of said piston for automatically controlling said operating means.

11. The combination with a tool and a fluid pressure motor for actuating the same, said motor comprising a fluid pressure cylinder having inlet and exhaust passages, a distributing valve for controlling said passages, and a piston in said cylinder, of a throttle valve in one of said exhaust pas sages, an operating member for said throttle valve, a striker for said operating member, and means operated by said tool for releasing said striker.

12. The combination with a tool and means for actuating the same, of means for check ing said actuating means, a lever for operating said checking means, a spring actuated rotary hub coaxially disposed with respect to the center of movement of'said lever, said hub having a flange provided with a shoulder adapted to strike said lever and with a stop shoulder, a detent for engaging said stop shoulder, and means operated by said tool for releasing said detent.

13. The combination with a tool and a fluid pressure motor for actuating said tool, said motor comprising a cylinder having inlet and exhaust passages, a distributing valve for controlling said passages, and a piston in said cylinder, of a rotary valve for controlling one of said exhaust passages, said valve having a stem, a bushing in which said stem is rotatably mounted, an operating lever secured to said stem, a spring actuated hub rotatably mounted on said bushing, said hub having a flange provided with a shoulder adapted to strike said lever and with a stop shoulder, a detent engaging said stop shoulder, and means operated by said tool upon abnormal movement thereof for releasing said detent.

14c. The combination with a percussive mechanism including relatively reciprocable cylinder and piston elements, a tool actuated thereby, andfluid distribution means therefor including inlet and exhaust passages, of means controlled by an abnormal stroke of said piston for automatically cushioning the percussive action thereof when said tool encounters a decreasing resistance, said automatic means including a member for controlling fluid flow through one of said passages, and a member actuated by said tool and adapted upon abnormal movement thereof to engage and operate said first named member.

15. The combination with a percussive mechanism including relatively reciprocable cylinder and piston elements, a tool actuated thereby, and fluid distribution means therefor including inlet and exhaust passages, of means controlled by an abnormal stroke of said piston for automatically cushioning the percussive action thereof when the tool encounters a decreasing resistance, said automatic means including an operating member therefor, a striker for said operating member, a detent for said striker, a member for releasing said detent, and a member actuated by said tool and adapted upon abnormal movement. thereof to engage and operate said detent releasing member.

16. The combination with a tool and -means'for actuating the same, of means for named lever and operatively connected with said vtool, said first named lever having a part engaged by said second lever upon abnormal movement of said tool. 3

17. The combination with, a tool and means for actuating the same, of means for checking said actuating means, an operating lever for said checking means, a spring actuated rotary hub coaxially disposed with respect to the center of movement of said lever, said hub having a flange provided with a shoulder adapted to strike said lever and with a stop shoulder, a detent for engaging said stop shoulder, a second lever operatively connected with said detent, and a third lever operatively connected with said tool, said second lever having a part engaged by said third lever and operated thereby to release said detent upon abnormal movement of said tool.

18. The combination with a tool and means for actuating the same, of means for checking said actuating means, a lever operatively connected with said checking means for controlling the same, a second lever mounted to swing about the axis of said first named lever and operatively connected with said tool, and an adjustable abutment screw carried by said hrst named lever and engaged by said second lever upon abnormal move ment of said tool to operate said first named lever and render operative said checking means.

19. The mechanism including relatively reciprocable cylinder and piston elements, a tool actuated thereby, and fluid distribution means there for, of means for checking an abnormal stroke of said piston including a trigger element normally manually set, and adapted when released to place said checking means in action, and means forsuddenly releasing the same on abnormal movement of said tool.

20. The combination with percussive mechanism of cylinder and piston elements, a tool operated thereby,and fluid distribution means therefor including inlet and exhaust passages, means for cushioning an abnormal blow of said piston comprising a valve in one of said passages, said valve being open during normal operation of saidmechanism, a spring held hub member for actuating said valve to closed position,

means operated by an abnormal motion ofsaid tool for releasing said hub member to actuate said valve, and manual means for actuating said valve independently of said hub member. 7

' In testimony whereof I a'fliX my signature.

HENRY H. MERCER.

combination with percussive 

